Why would cosmologists, philosophers, astronomers and particle physicists gather to talk about symmetry? It sounds odd. But symmetry in a law of nature implies something extremely powerful and beloved of physicists: conservation.

It is a difficult concept though. To make life easier, consider Newton’s classical mechanics, via an experiment of throwing a ball. We get the same result in London as in Sydney, showing Newton’s ideas have “translational symmetry” – it doesn’t matter where we move the experiment.